<!DOCTYPE html>
<html>
    <head>
        <style>
            .container {
                display: flex;
                height: 500px;
                width: 500px;
                background-color: antiquewhite;
                align-items: flex-end;
            }

            .container > * {
                text-align: center;
                width: 100px;
                margin: 0 30px;
                background-color: aquamarine;
            }  

            .item1 {
                height: 100px;
            }

            .item2 {
                height: 200px;
            }

            .item3 {
                height: 300px;
            }


        </style>
    </head>
    <body>
        <div class="container">
            <div class="item1">item1</div>
            <div class="item2">item2</div>
            <div class="item3">item3</div>
        </div>
    </body>
</html>